珙桐开花动态及繁育系统的研究

Study on Flowering Dynamics and Breeding System of Davidia involucrata Baill

通过野外观察，运用杂交指数、花粉-胚殊比、人工授粉和套袋等方法，对珙桐的开花状态、繁育系统进行研究。结果表明，种群平均花期为26d，但同一地点的不同年份，相同年份的不同地点均有所不同；同一棵树树冠预部枝条和基部枝条开花时间也有差异。花序从开始散粉到散粉末期一般持续8-10d，开花过程中柱头高于花药的位置，雄花的花药散粉时间早，两性花2-3d。两性花柱头具可授性的时间早两性花花药开裂1-2d。由于其杂交指数等于4，花粉-胚珠比等于14885.2，结合人工套袋和授粉试验结果确定该种的繁育系统以异交为主，还有一定程度的自交。花粉竞争可能是珙桐结籽率低的原因之一。

Through wild observation, the study researches the flowering dynamics and breeding system of Davidia involucrata Baill by using outerossing index, ration of pollen and ovule, Lagging and other methods. The research showed that mean flowering period of population is 26 days, it is different among years in the same position, also among different posotions in the same year, there is difference between the top and the base branch in the stone tree. Inflorescence lasts about 8 to 10 clays from initial pollinating to the end, the stigma is longer than the anther in the process of flowering, the pollinating time of male anther is earlier 2 to 3 days than bisexual flower. The stigma receptivity time of bisexual flower is earlier 1 to 2 days than anther dehiscence time of bisexual flower. Because the outerossing index is 4, the ratio of pollen and ovule is 14885.2, combined with the test results of artificial bagging and pollination, the study conclude the breeding system belongs to outcrossing, partially self-compatible. Pollen competition may he a factor leading to the low rate of seed setting of Davidia invobucrata Baill.